Control system for submersible motors and the like



y 16, 1939- E. MENDENHALL ET AL 2,158,472

CONTROL SYSTEM FOR SUBIERSIBLE MOTORS AND THE LIKE Original Filed Aug.28, 1934 3 Sheets-Sheet l y 1 E. MENDENHALL- ET AL 2,158,472

CONTROL SYSTEM FOR SUBMERSIBLE MOTORS AND THE LIKE Original Filed Aug28, 1934 s Sheets-Sheet 2 May 16, 1939. E MENDENHALL ET AL 2,158,472

CONTROL SYSTEM FOR SUBMERSIBLE MOTORS AND THE LIKE Original Filed Aug.28, 1934 5 Sheets-Sheet 3 Patented May 16, 1939 UNITED STATES PATENTorrlcs CONTROL SYSTEM FOR SUBMEBSIBLE H- TOBS AND THE LIKE EarlMendenhall. Loo Anselel, and Janina B. Van Horn, Alhambra, Calit,aaaignors to Byron Jackson 00., Huntington Park, Calif, a corporation ofDelaware SClainI.

Our invention relates to the art oi controlling submersible electricmotors and the like in response to the conditions existing therein, orfor otherwise indicating the existence of such conditions, and consistsin novel methods and apparatus for accomplishing such ends, and is adivision of our copending application Serial No. 741,796, filed August28, 1934, which issued on December 14, 1937, as Patent Number 2,102,018.

In the preferred embodiment a shell is provided which contains aninternal liquid, usually oi dielectric character and having accessthrough one means or another with a conducting liquid, usually theexternal liquid in which the shell is submerged. Excessive amounts ofsuch conducting liquid should not be allowed to enter the shell, and itis an important object of the present invention to provide a systemfunctioning in response to the relative amounts of the dielectric 2-)and conducting liquids in the shell, and to provide a novel method ofcontrolling a structure such as a submersible motor, or otherwiseindicating adverse conditions therein.

In one embodiment of the invention bodies of :5 the liquids may bemaintained in the shell in contact with each other. Experiments haveshown that even if the surface of contact therebetween is maintainedquiescent, there is a tendency for the dielectric liquid to be slightlycon- 30 taminated by the conducting liquid, this action apparentlytaking place through a molecular interchange at the surface of contact.There are several ways of slowing up or preventing this contamination atthe surface of contact, but should 3 such means fail to function it isdesirable to be able to control the structure so that no detrimentalresults will take place. In other instances the dielectric liquid maybecome contaminated through a defective sealing action. However, re-

gardless of how this contamination takes place,

the resulting condition is one in which the relative amounts of the twoliquids in the shell is not correct, too much of the conducting liquidbeing present. It is an object of the present invention to provide amethod and apparatus for indicating this condition to the operator, orto automatically control the system in response to such conditions.

In other instances the excessive amount of the conducting liquid in theshell may exist due to contraction or leakage of the dielectric liquidfrom the shell, thus allowing the body of conducting liquid to increasein size proportionately. Further objects of the invention lie in thepro- 55 vision of a system which indicates such a condition to theoperator or which controls the structure in accordance with suchconditions.

When the invention is applied to a submersible electric motor, it isdesirable to de-energize the motor should an excessive amount of theexternal liquid enter the motor shell, and it is an object of thepresent invention to provide such a method and apparatus.

Such a control system may conveniently include one or more electrodesextending in the dielectric liquid toward the surface of contact of thedielectric liquid and conducting liquid, these electrodes being includedin one or more control circuits, and it is an object of the presentinvention to provide one or more of such control circuits which can beused either for indicating purposes or control purposes.

In many systems wherein an electric means such as an electric motor ispositioned inside a shell containing a dielectric liquid, the dielectricproperties must be maintained to prevent electrical failure of the motoror other electric means. Even extremely minute and almost infinitesimalquantities of conducting liquid must be elimihated, and it is an objectof the present invention to provide a novel structure responsive toextremely minute quantities of such a conducting liquid present in adielectric liquid, and, in some instances, to use this structure forcontrol or indicating purposes.

One form of such a structure which we have found particularly desirableincludes a pair of conductor means spaced from each other in thedielectric liquid so that the current between these conductor meansvaries in response to the quantity of contaminating liquid present inthe dielectric liquid. The provision of a novel form oi such a structureis included among the objects of the present invention.

Such a structure is extremely sensitive, especially if a material ispositioned between the conductor means which has an aifinity for theconducting liquid. Even the minute quantity oi moisture appearing inones breath is suiilcient to very markedly change the amount of currentflowing between the conductor means in such a structure, and it is anobject of the present invention to provide such a pair of conductormeans of novel form between which is positioned a material having anailinity for the contaminated or conducting liquid.

This structure is so sensitive that diiliculty is sometimes encountereddue to the minute amount of moisture which condenses on the inner wallsof the shell during or immediately after installation, this minuteamount of moisture being sumcient to actuate the control or indicatingsystem. In a submersible motor this extremely minute amount of moistureis usually unobjectionable and, in fact, the dielectric liquid appearsto increase in dielectric strength when the motor has been energized fora time. If the structure is too sensitive its operation may be socritical that it is responsive to a temporary adverse condition whichwould be overcome upon continued operation of the motor or otherelectric means. To overcome this difficulty we have provided anauxiliary circuit capable of drying out the structure or otherwiseremoving at least a portion of the contaminating liquid from thematerial having aflinity therefor. If the adverse condition is notcleared up, the structure will later give another indication throughincrease in current.

However, if the condition has been corrected, no

further indication will be given by this structure. It is an object ofthe present invention to provide a structure responsive to the amount ofcontaminating material in the dielectric liquid, and which includesthese or equivalent features.

It is a further object of the invention to provide such a structure inwhich the sensitivity can be controlled.

Another object of the invention is to provide a system utilizing theconductors supplying current to the motor or other electric means forcontrol purposes, and to provide such a system in which the unbalancingof any phase of a multiphase supply circuit is detected and used forcontrol or indicating purposes.

Other objects and advantages of the invention will be evident to thoseskilled in the art from the following description.

For purpose of illustration and definiteness the invention will behereinafter described with reference to a submersible electric motorstructure. It should be understood, however, that the principles hereindisclosed can be used in other capacities or for controlling othermeans, or can be used in other types of installations regardless ofwhether or not these installations are submerged.

Referring to the drawings,

Fig. 1 illustrates a submersible motor-pump unit installed in a well andincorporating certain of the control devices of our invention.

Fig. 2 is a wiring diagram of the apparatus illustrated in Fig. 1.

Figs. 3, 4, and 5 are wiring diagrams of alternative forms of theinvention.

Fig. 6 is a fragmentary view illustrating the moisture-indicatingstructure.

Figs. '7 and 8 illustrate alternative forms of the moisture-indicatingstructure.

Fig. 9 is a wiring diagram of an alternative farm of control systemutilizing the structure s own in Fig. 8.

Referring particularly to Fig. 1, we have illus trated a well casing llpositioned in a well and filled with water or other conducting liquid toa level indicated by the numeral l2. Supported in the well by adischarge pipe l5 extending downward therein is a pump unit l6 to thelower end of which is secured a motor shell both the pump unit and themotor shell being below the surface l2. This pump unit'may be of aconventional turbine type, drawing well liquid thereinto, as indicatedby the arrows ll, and discharging this liquid upward through thedischarge pipe IS. A motor 20 drives the runners of the pump unit I6through a shaft 2| extending through a arcane wall 22 of the motor shellI1, this shaft being sealed relative to this wall by a suitable sealingdevice 23. This sealing device is preferably of the mercury-sealed type,but could be replaced by any seal which effectively prevents water fromentering the motor shell I! at the junction of the shaft 2| and the wall22. The motor 20 is positioned in a motor chamber 24 of the motor shellI1 and comprises the usual stator 25 and rotor 25, the latter beingjournalled in suitable bearings, such as those illustrated.

A balance or expansion-permitting chamber is formed in the lower end ofthe motor shell ll, the upper end of this chamber being defined by abaiile II extending thereacross. This baflle includes one or moreopenings 32 which communicate between the motor chamber 24 and the upperend of the balance chamber 30. The lower end of this balance chamber isin open communication with the external liquid in the well through anopening 33 or other equivalent means.

In open communication with the interior of the motor shell I1, and thusin open communication withv the motor chamber 24 and the upper end ofthe balance chamber 30 is a pipe 35 which extends upward to the surfaceof the ground, this pipe carrying the conductors supplying the currentto the motor and also the control conductors to be hereinafterdescribed, these conductors being of such diameter as to not completelyfill. the pipe 35 so that the space around these conductors is open.

The upper end of the balance chamber and A the motor chamber 24 containa dielectric liquid such as dry oil. The balance chamber 30 thuscontains pressure-equalized bodies of the dielectric liquid and theexternal or conducting liquid, these bodies being in contact at asurface 31. Due to the equalization of pressures between the dielectricliquid and the external or conducting liquid, the dielectric liquidextends in the pipe 35 to a level 39. v The level 39 is usually slightlyhigher than the level l2 due to a difference-in density between thedielectric liquid and the external or conducting liquid, the formerbeing usually of less density than the latter.

This system is very advantageous for it forms a dynamic system whereinthe internal and external pressures on the shell I! are alwaysmaintained substantially equal regardless of the position of the levell2. Thus, when the pump unit I 6 is put into operation the level l2drops, thus lowering the pressure on the external or conducting liquidin the balance chamber 30, and thus correspondingly lowering the level39 of the dielectric liquid in the pipe 35. A corresponding amount ofexternal or conducting liquid is forced ment of the surface 31 in thebalance chamber being slight.

If, however, any contraction or leakage of dielectric liquid from themotor chamber takes place, or if a sufilcient amount of .dielectricliquid is not supplied to the motor chamber in the first place, it ispossible that the surface 31 may rise to such a point as to allow theexternal or conducting liquid to pass through the opening 32 and thuseventually into contact with the windings of the motor 20. This would,of course, short-circuit these windings and necessitate the renewalthereof after the motor pump unit had been removed from the well. Itthus becomes desirable to provide means responsive to the relativequantities of the two liquids in the motor shell and either indicatingthe adverse condition or remedying it.

The surface 31 may, of course, be lowered at any time by pouring anadditional supply of dielectric liquid into the upper end of the pipeII,-

this additional supply forcing the surface 31 downward and at the sametime maintaining the equalization of pressures in the system. It is,however, desirable that thissupply of dielectric liquid be accomplishedautomatically, and in Figs. 1 and 2 we have shown a system wherein thismay be accomplished. In accomplishing this result it is necessary toprovide some means opcrating as a function of the relative amounts ofthe two liquids in the motor shell l1. and in Figs.

1 and 2 we have illustrated this means as com-' prising an electrode 44extending downward through an insulator from the baifle II. A conductor4| is connected to this electrode and extends upward to the surface ofthe ground through the pipe 45, being connected to one terminal of asolenoid 42 associated with a magnetic valve 43, the other terminal ofthis solenoid being connected by a conductor 44 to a conductor 45 of athree-phase supply line including conductors 46 and 41, the last-namedconductor being grounded as indicated by the numeral 44. When thesurface I'l comes in contact with the electrode 44 a circuit is thuscompleted from the conductor 41 through ground, through the body ofexternal or conducting liquid in the balance chamber, and through theelectrode 40, conductor 4|, the solenoid 42, and the conductor 44. Thisenergizes the solenoid and opens the valve 43 to allow dielectric liquidto move downward in the pipe 35 from a supply tank so. This supply ofdielectric liquid continues until the surface 31 is lowered from theelectrode 40 at which time the circuit through the solenoid 42 is brokenand the valve 43 again closes.

In the event that the supply tank 49 should be dry, or in the event thatthe valve 43 did not function, it would be desirable to lower thesurface 31 by other means. To accomplish this end we position a secondelectrode 50 in the balance chambef and connect this second electrode toa conductor which extends upward and is connected to one terminal of asolenoid 52 of a magnetic valve 53, the other terminal being connectedto the conductor 44, as shown in Fig. 2. The valve 53 may control thesupply of air or other liquid or gaseous medium from a storage means 55to the pipe 35. Thus, if the surface 31 comes into contact with theelectrode 50, a circult is completed from the conductor 41 through thebody of external or conducting liquid in the balance chamber and throughthe electrode 50, conductor 5|, solenoid 52, and conductor 44, therebyopening the magnetic valve 53, and allowing compressed air or othermedium from the storage means 55 to be introduced into the pipe 35. Thisforces the level of the dielectric medium in the pipe 35 downward but assoon as the surface 31 breaks contact with the electrode 50, the

I valve 53 closes.

Ifagassupplyisusedwithsuchasystemas distinct from a liquid supply fromthe storage means II, the upper end of the pipe 51 may include a valvel0 forming a restricted passage to allow pressure to be built up in thepipe 35 when gas is supplied thereto, a portion of this gas escapingupward through the restricted passage and thus giving an indication ofthe condition of the structure. Such a restricted passage will stillpermit open communication between the pipe 35 and the atmosphere topermit compensation in the amount of air in this pipe upon the slowershift in conditions effected by a change in the level II. In otherinstances the pipe 85 can be closed from the atmosphere by eliminatingthe pipe 51 or closing the valve 54 and having the pothead 55 closingthe pipe 35. In this in stance the air in the pipe 45 will be slightlycompressed or rarefied with change in the level 39. Oil or other liquidunder pressure may be then used in the supply means 49 or 55 or both,these supply means being closed from the atmosphere.

Should the level 31 continue to rise, however, due to a failure of boththe supply means, it is desirable to automatically de-energize themotor. This is accomplished by an electrode 60 extending into thebalance chamber a distance less than the electrodes 40 and 50. Aconductor Si is connected to the electrode and extends through astructure responsive to the amount of external or conducting liquidcontaminating the dielectric liquid, this structure being hereinaftertermed a moisture-indicating relay 62 for deflniteness. This relay 6! ispositioned in the motor chamber preferably adjacent the stator windingand the current flowing through the conductor 6| thereafter flows upwardto the surface of the ground to one terminal of a solenoid 63, the otherter minal thereof being connected to the conductor 45. The solenoid 63may operate any control or indicating device, but is shown as beingassociated with a relay providing contacts 65 which form a part of aholding circuit for a main switch 66, this holding circuit alsoincluding a holding coil or solenoid 61 of the usual construction, thisholding circuit being of a conventional type whereby energization of thesolenoid 61 closes and maintains closed the main switch 66, thussupplying current from the conductors 45, 46, and 41 to intermediateconductors 10, H, and I2 extending downward through the pipe 35 andbeing connected to the stator winding.

In Fig. 2 we have shown one type of holding circuit including a startingswitch 13, one terminal of which is connected to the conductor 45, andthe other terminal of which is connected to an auxiliary switch I4 andto one of the relay contacts 65. Closing the switch 13 sends currentfrom the conductor 45 through these relay contacts and through thesolenoid 61 to the conductor 46, thus closing the main switch 66. Assoon as this switch is closed the auxiliary switch 14 likewise closesand when the starting switch 13 is opened the holding circuit of theswitch is maintained by current passing through the main switch andthrough the auxiliary switch from the conductor 10, the currentreturning to the conductor 46 through the relay contacts 65 and theholding coil 61, as previously described. Should the level 31 come intocontact with the electrode 50 a circuit will be completed from theconductor 41 through the body of external liquid in the balance chamberand through this electrode, the conductor GI, and the solenoid 63, tothe conductor 45. This energizes the solenoid 63 and opens the relaycontacts 65. This deenergizes the holding circuit of the main switch 66and allows this switch to move into open position shown in Fig, 2.

In addition, however, it is sometimes desirable to close an alarmcircuit 16 including a bell 11 or other indicating means when thiscondition occurs, and in accomplishing this end we utilize contacts 18on the relay, which contacts are closed when the solenoid 63 isenergized, thus completing a circuit from the conductor 45 through thecontacts 18 and through the circuit 16 and the bell 11, the currentreturning to the conductor 46. The attention of the operator is at oncecalled to this condition, and should he attempt to start the motor byclosing the starting switch 13, no harm will result in view of the factthat the holding circuit of the switch cannot be closed due to the relayopening the contacts 65.

The moisture-indicating relay 82 is also a means responsive to therelative amounts of said dielectric liquid and external or conductingliquid in the motor shell [1, this relay being responsive primarily tothe amount of the contaminating liquid which has become associated withthe dielectric liquid. It will also function should the surface 31 riseto this relay. Such contamination may take place through several factorssuch as leakage of conducting liquid through imperfections in the motorshell or leakage through the seal 23, especially if certain types ofseals are utilized. In addition, under unfavorable conditions there maybe a slight contamination of the dielectric liquid at the surface 31,especially if portions of the interior of the shell H are not heated asby the presence of the motor 20 or other means.

The dielectric liquid is continuously circulated by the rotation of therotor 26 or by other means, being moved through circulation paths suchas indicated by the arrows 11a of Fig. 1, this being desirable in viewof the cooling action exerted on the motor or other electric means.While this circulation is very desirable in this regard, it also servesto distribute any contaminating particles throughout the shell II. Itthus becomes desirable to know the condition of the dielectric liquidand the relative amounts of the two liquids in the material beingcirculated. The moisture-indicating relay 82 may be used in thiscapacity, being preferably positioned in the path of the circulatingliquid and near the motor winding. i

This relay 62 is of very simple construction and may include any twoconductor means spaced from each other in the dielectric liquid so thatthe current flowing therebetween varies with the amount of conductingliquid in the dielectric liquid. The change in current can be used forindicating or control purposes, for instance in operating the magneticvalves 43 or 53, in operating a disconnect means as by opening theholding circuit of the switch 66, or in operating any visible or audibleindicating means.

In practice this moisture-indicating relay 62 may be formed in a mannerindicated in Fig. 6 by utilizing two cotton-covered conductor meanstwisted together so that the cotton insulation is positioned between theconductor means. The cotton covering on these conductor means has anaffinity for any 01 the conducting liquid present in the dielectricliquid. In this embodiment there is impressed between the conductormeans a potential, so that when the cotton covering attracts theconducting liquid which may be present in the dielectric liquid, theresistance between the conductors is decreased, thus changing thecurrent flowing through any control circuit or any indicating circuitwhich may be connected to the moisture-indicating relay 62. In theembodiment shown one of the conductor means of this relay may beconnected in series with the intermediate portion of the conductor 6| soas to form a part thereof, while one end oi the other conductor means isgrounded to some portion of the motor shell H, the other end of thisother conductor means being electrically unconnected. With this form 01'connection the potential between the conductors 45 and 41 is impressedacross the conductor means so that decrease in the resistance betweenthe conductor means will efl'ect an increase in the current flowing in acircuit from the conductor 41 through ground and through one of theconductor means, thence to the other of the conductor means andreturning to the line through the conductor GI and the solenoid 63. I1this current becomes suiflciently large, the solenoid will be operatedand the switch 66 opened, as previously described. The motor cannotagain be energized until the adverse condition is corrected, as bysupplying additional dielectric medium to the pipe 35 in sufllcientquantities to replace or dilute the existing contaminated dielectricliquid, and until the moisture content of the cotton-covered insulationis decreased. This decrease in moisture content is in some instancesautomatically effected due to the heating action between the twoconductor means of the moisture-indicating relay 62. In other instancesit is necessary to force an auxiliary current therethrough to effectthis drying action, or in extreme instances to remove the motor-pumpunit from the well. It is not, however, necessary that we use cotton asan insulating medium, though this type of relay has been found to beboth cheap and very effective in practice. Other types of insulatingmedia may be utilized, whether or not the particular medium used has aselective afllnity for the conducting liquid.

If the motor pump is not used for long periods of time, it isconceivable that the dielectric liquid may become contaminated with theexternal or conducting liquid to such an extent that to start the motorwould be detrimental. The moisture-indicating relay 62' will ordinarilytake care 01' such a situation, but in the event that such a relay isnot used or in the event that it becomes temporarily inoperative, weprefer to utilize an auxiliary relay 83 providing a solenoid winding 84connected between the conductors 46 and H and thus around the mainswitch 66. This relay provides contacts 86 which are closed when thesolenoid winding 84 is energized, thus closing an alarm circuit 81including a bell or other alarm means 88. Assuming that the dielectricliquid becomes contaminated around the motor windings, it will at oncebe apparent that current will flow from the switch 66 through thesolenoid winding 84 and through the conductor H to the motor winding. Ifthe amount or contamination has become suflicient to carry a minuteamount of current from any phase of the motor winding to ground, currentwill flow through the conductor H and will return through the groundedmotor shell II to the conductor 41, thus energizing the solenoid winding84 and closing the alarm circult.

In Fig. 3 we have shown the solenoid winding Northauxiliaryrelayflasbeingassociated with the relay in the holding circuitof the switch so that energiaatlon of the solenoid winding 04 will makeit impossible to start motor even though the starting switch is .00 orbecause a circuit has been completed through the solenoid 04 due tocurrent passing from the winding of the motor to the grounded shell. aspreviously described. Thus, the system showninl'ig.3eliminatutheuseofanauxiiiary alarm circuit 01.

In Fig. 4 we have shown still another system which is simpler than thesystem shown in Fig. 2. In this system only a single electrode need beused, this electrode being indicated by the numeral I00 and beingconnected to a conductor Ill which may in turn be connected to amoistureindicating relay, as previously described. The conductor IIIalso conducts current to a solenoid winding I02 of a magnetic valve I00controlling the flow from a supply tank I04 in a manner previouslydescribed. The solenoid I02 is also connected through a conductor I05 toone terminal of a solenoid ill, the other terminal being connected by aconductor I00 to the conductor 45 of the supply line.

In this form of the invention, when the surface 01 comes into contactwith the electrode I00, the solenoids I02 and I01 are simultaneouslyenergized and remain energized until the surface 01 movesout of contactwith the electrode I00. The energizing of the solenoid I02 opens thevalve I00 and allows dielectric liquid or other material to be suppliedthrough the pipe 00, as previously described. The energization of thesolenoid I0l exerts a force on a plunger H0 in a rightward direction,this movement being opposed by the action of a dashpot III which may beof any desired construction. So long as the solenoid I0l remainsenergized, however, the plunger IIO moves slowly to the right and aftera predetermined length of time, a pallet I I2 on the plunger I I0bridges acros contacts I I0, thus completing a circuit from theconductor 45 through the solenoid 00 of the relay associated with theholding circuit, the current returning to the conductor 40 of the supplyline. This, of course, opens the main switch and de-energizes the motor.

In the form of the invention shown in Fig. 4, if the dielectric liquidsupplied through the pipe 05 does not lower the surface 01 within apredestarting switch I0 in the usual manner. The

time-limitrelaydisclosedinl'ig.4is,ofoourse,

diagrammatic and other forms of time-operated switches may be utilized.

In Fig. 5 we have illustrated a system wherein no auxiliary controlwires are necessary, the only wires extending through the pipe 05 beingthe conductors 10, ll, and I2. In this form of the invention we providean electrode I20 connected to a conductor I 2I which is ccnnected to theconductor I0 in the motor chamber. Each of the conductors 10, II, and I2has associated therewith a current transformer, and the object or thesystem shown in Fig. 5 is to de-energiae the motor when the current inthe phases becomes unbalanced. This will, of course, take place when thesurface 01 contacts the electrode I20, at which time the current in theconductor I0 is increased due to a circuit being formed from theconductor 41 through the body of external liquid in the balance chamberand through the electrode I20 and the conductor I2I.

Any relay system may be utilized for determining when such an unbalancedcondition exists. In Fig. 5 we have shown one system, indicating thecurrent transformers associated with the conductors 10, II, and 12 bythe numerals I00, HI, and I02 respectively. These current transformersare connected to solenoids I00, I00, and I01 respectively, which aredisposed 120 apart, the inner faces of which are spaced from each otheras diagrammatically shown in Fig. 5. Extending between these inner facesis an armature I40 which has been shown as being triangular in shape. Asshown to the left in Fig. 5, this triangle-shaped armature I40 isconnected to a ball I journalled in a socket I42. Extending from thisball is a support I40 which normally engages the lower end of a plungerI44 of an auxiliary relay I 45 including contacts I46 forming a part ofthe holding circuit of the main switch. The contacts I40 are normallyclosed by a pallet I41 associated with the plunger I 44, but if thesupport I40 is moved to pne side, as indicated by the dotted line I48,the plunger I44 will drop, thus breaking the holding circuit of theswitch 06. Such a movement of the support I40 takes place when thetriangle-shaped armature I 40 is moved from its central position withrelation to the solenoids I05, I06, and I31. Normally, when the threephases of the system are balanced the armature I40 will be spacedequally from each of the solenoids. If, however, the current through theconductor I0 becomes greater than the current through the conductors IIor I2, for instance, the solenoid I05 will exert a greater pull on thearmature I40 and will draw this armature toward the core of thissolenoid, thereby moving the support I 40 into its dotted line positionI40 and thereby allowing the plunger I44 to drop to de-energize theholding circuit. This at once de-energizes the motor and the motorcannot be again energized until the auxiliary relay I45 is manuallyreset.

In other instances alternative forms of the moisture-indicating relay 62can be used in conjunction with any of the systems hereinbef oredescribed. It has been found that the type of moisture-indicating relayillustrated in Fig. 6 is extremely sensitive. Sensitivity is, of course,essential, for we have found that one part of conducting liquid in tenthousand parts of the dielectric liquid will produce suflicientcontamination to detrimentally affect and in some instances burn out themotor or other electric means. However, the moisture-indicating relayshown in Fig. 6 is responsive to much smaller quantities of thecontaminating liquid. Experiments have shown that when a submersibleelectric motor, for instance, is first installed, the dielectricstrength of the dielectric liquid will decrease until the motor has beenoperated for a period ofntime, after which the dielectric strength againincreases and in some instances becomes even greater than when thestructure was originally installed. This slight temporary decrease indielectric strength immediately after installation we attribute to theslight amount of moisture which condenses on the walls of the motorshell and on the other parts of the structure which contaminates thedielectric liquid. The subsequent increase in dielectric strength is nodoubt due to the purifying action of the heat generated when the motoror other electric means is operating, together with the circulationsystem shown. The maintenance of differential temperatures in differentportions of the motor shell appears to be a factor in this regard,especially as to preventing contamination adjacent the surface 31, thiscontamination being apparently effected through a molecular interchangeat the surface of contact. With the type of moisture-indicating relayshown in Fig. 6, the preliminary or temporary decrease in dielectricstrength is often sufficient to operate this extremely sensitive device,thus giving an indication of a condition which would automaticallycorrect itself should the motor continue to operate. It thus becomesdesirable in some instances to use a less sensitive moisture-indicatingdevice. Such alternative devices are illustrated in Figs. '7, 8, and 9.

Referring particularly to Fig. 7, a moistureindicating relay is shown asincluding a pair of conductor means I18 and III each-formed of ametallic plate preferably perforated as shown. Positioned between theseconductor means is a member I12, which, if desired, may be made of asubstance having an afflnity for the contaminating liquid. In thisconnection we find it very satisfactory to use a strip of fiber in thisregard, different fibers producing different sensitivities. One of theseconductor means may be grounded as indicated by the numeral I13 and theother may be connected to a conductor IIl corresponding to the conductor8| of Fig. 2. If desired, an electrode 68 may be used and connectedtothe conductor II to perform the functions previously set forth.

Another form of moisture-indicating relay which is often desirable isillustrated in Fig. 8. Here two conductor means I 88 and I8I areutilized. The conductor means I88 is formed of a metallic plate or rod,preferably perforated as shown. The conductor means I 8| may take theform of a coil of resistance wire disposed around the conductor means I88. Members I82 and I83 are positioned on opposite sides of theconductor means I88 and separate this conductor means from the coil ofresistance wire. These members I82 and I88 may be formed of a materialhaving an afllnity for the contaminating liquid, fiber being verysatisfactory in this regard, although other substances can be used.

Fig. 9 illustrates one mode of connecting the moisture-indicating relayshown in Fig. 8. A conductor I85 corresponding to the conductor 8| ofFig. 2 is electrically connected to the conductor means I88, and mayalso be connected to the electrode 88. One terminal of the coil ofresistance wire I8I is grounded as indicated by the numeral I88, theother terminal being connected to a conductor I81 which extends upwardin circuit with the secondary winding of the transformer I 98 oneterminal of which is grounded as indicated by the numeral I8I, therebeing a switch I82 in this circuit. The primary winding of thetransformer I88 is connected between the conductors 48 and 41. Theswitch I92 is normally open during the operation of the structure. Evenwhen the dielectric strength of the dielectric liquid is entirelysatisfactory a minute current will flow from the conductor 41 throughground, through the conductor I86, and thence through the members I 82and I83 to the conductor means I88 of the moisture-indicating'relay,returning to the conductor through the conductor I85 and the solenoidwinding 63. This current will not, however, be sufficient to open theholding circuit of the switch 68. Should the dielectric liquid becomecontaminated, the current through this circuit will increase insufiicient quantity to open the switch 68.

It is desirable to be able to ascertain whether or not this adversecondition is only a temporary one which would automatically clear up onfurther operation of the motor, or whether additional dielectric liquidshould be supplied. In

effecting this end the switch I82 may be closed to complete an auxiliarycircuit from the transformer I88 through ground and through the coil ofresistance wire I8I, the current returning to the transformer throughthe conductor I81 and the switch I92. This auxiliary or heating circuitdelivers sufilcient current to the coil of resistance wire to locallyheat the moisture-indicating relay sufficiently to drive out at least aportion of the conducting liquid which may have become associated withthe members I82 or I83. It is not es sential to actually vaporize thisconducting liquid, though this can be done if desired. Usually it issuflicient to pass a small current through the coil of resistance wireto produce a localized increase in temperature sufficient to expel aportion of the conducting liquid which has become associated with thesemembers I82 and I88. Thereafter the switch 86 can be again closti andthe motor set into operation. If further opera tion of the motor doesnot alleviate the adverse condition the moisture-indicating relay willagain operate, thus indicating that a(- iitional dielectric liquidshould be supplied or that other means should be used to correct thedifficulty. If, however, the motor continues to operate without beingde-energized by the moisture-indicating relay, it is a clear indicationthat the adverse condition was only temporary. Should an excessiveamount of the conducting liquid again become associated with thedielectric liquid, the moisture-indicating relay will, of course,operate to de-energize the motor.

While in Fig. 9 we have shown only two control conductors I85 and I8!extending upward to the top of the well, it will be clear that theconductor I85 serves a dual purpose in conducting current either fromthe electrode 68 or the moisture-indicating device. It is thus sometimesdesirable to use two separate conductors in place of the singleconductor I85, one extending up-- ward from the electrode 68 and theother from the conductor means I88 of the moisture-indicating relay.Such conductors may be used for separate control or indicating purposes,but preferably are both connected to the relay 82 for deenergizing themotor.

It should be clearly understood that the moisture-indicating relay canbe used for purposes of indication as well as direct control. In thisconnection the pallet switch operated by the solenoid Winding 63 can bevisually observed, or any other suitable indicating means can beconnected in circuit with the moisture-indicating relay. It should alsobe clear that various features oi! the invention can be usedindividually. Thus, it is not always essential that a system be providedwhich will supply both dielectric oil or air or other medium to themotor. In many installations we install only the means for supplyingadditional dielectric liquid to the motor. In still other installationsit is possible to dispense with this means for supplying dielectricliquid, and utilize only the electrode for de-energizing the motor orfor indicating the presence of an adverse condition. In some instanceseven this electrode can be dispensed with and the moisture-indicatingrelay utilized to indicate an undesirable increase in relative amountsof the liquids in the motor shell, either through a rise in level of thesurface 31 so that the conductor means of the moisture-indicating relayare short-circuited, or by the presence of excessive amounts ofcontaminated material dispersed in the dielectric liquid. In otherinstances it is possible to utilize only one or more electrodes 40, 50,or 60 for. control or indicating purposes regardless of the presence ofthe moisture-indicating relay 62. In this connection any of theseelectrodes, in effect, act in a manner somewhat analogous to themoisture-indicating relay it through molecular interchange at thesurface 31, the material between this surface and the electrode becomescontaminated with conducting liquid in suflicient degree to permit acurrent flow between the surface 31 and this electrode even though thesurface 31 does not directly contact the electrode. In this instance theelectrode corresponds to one of the conductor means of themoisture-indicating relay, while the body of conducting liquidcorresponds to the other conductor means. Such a system is not, however,as sensitive as the moisture-indicating relay shown in Figs. 6, '7, or8.

It will be understood that the particular apparatus illustrated has beenshown only diagrammatically, and that many modifications in theapparatus, as well as in the circuits utilized can be made withoutdeparting from the spirit 01' this invention. Thus, more sensitiverelays or other amplifying devices can be incorporated in the controlcircuits in addition to the apparatus shown. So also, if localregulations prevent the grounding of one of the supply conductors, thepotentials utilized for control or indicating purposes can be obtainedfrom auxiliary sources, such as batteries or transformers, one terminalof which can be grounded if desired.

Application 741,796, which issued on December 14, 1937, as Patent2,102,018, is a continuationin-part of our co-pending application SerialNo. 524,494 filed March 23, 1931, now Patent No. 2,002,912.

We claim:

1. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid; an electric motor insaid shell; a multi-phase circuit supplying current to said electricmotor; means in said shell and responsive to the amount of saidconducting liquid therein for unbalancing the phase currents in saidcircuit; and means responsive to the unbalancing of said phase ourrentsfor controlling said submersible electric motor structure.

2. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid; an electric motor insaid shell; conductor means supplying current to said electric motorincluding a plurality of conductors; means responsive to the amount ofsaid conducting liquid in said shell whereby the amount of currentflowing in one of said conductors is changed when the amount ofconducting liquid in said shell changes; and means responsive to saidchange in the amount of current flowing in said one conductor resultingfrom a change in the amount of conducting liquid in said shell forcontrolling the operation of said motor.

3. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid; an electric motor insaid shell; conductor means supplying current to said electric motorinclud ing a plurality of conductors; means for de-energizing saidmotor; and means connected to one of said conductors so that a change incurrent flowing in said one conductor relative to the" current flowingin the other conductors will actuate said de-energizing means to stopsaid liquid having access to said conducting liquid,

an electric motor in said shell, a multi-phase circuit supplying currentto said electric motor, means in said shell and responsive to the amountof said conducting liquid therein for unbalancing the phase currents insaid circuit, and means responsive to the unbalancing of said phasecurrents for de-energizing said electric motor.

5. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid, a shell containing a dielectricliquid having access to said conducting liquid, an electric motor insaid shell, conductor means supplying current to said electric motorincluding a plurality of conductors, means responsive to the amount ofsaid conducting liquid in said shell whereby the amount of currentflowing in one of said conductors is changed when the amount ofconducting liquid in said shell changes, and means responsive to saidchange in the amount of current flowing in said one conductor relativeto the other of said conductors for deenergizing said electric motor.

6. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid, an electric motor insaid shell, a multi-phase circuit supplying current to said electricmotor, circuit de-energizing means included in said multi-phase circuit,means in said shell and responsive to the amount of said conductingliquid therein for unbalancing the phase currents in said circuit, andmeans responsive to the unbalancing of said phase currents for actuatingsaid circuit de-energizing means to de-energize said multi-phasecircuit.

'7. In combination in a submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid,

an electric motor in said shell, 8, multi-phase circuit supplyingcurrent to said electric motor, means in said shell and responsive tothe development of an adverse condition in the shell for unbalancing thephase current in said circuit, and means responsive to the unbalancingof said phase currents for controlling said electric motor.

8. In combination in a. submersible electric motor structure adapted tobe submerged in a conducting liquid: a shell containing a dielectricliquid having access to said conducting liquid, an electric motor insaid shell, conducting means supplying current to said electric motorincluding a plurality of conductors, means responsive to an adversecondition in the shell whereby the amount of current flowing in one ofsaid conductors is changed relative to the flow of current through theother of said conductors, and means responsive to said change in theamount of current flowing in one of said conductors relative to theother of said conductors for controlling the operation of said motor.

EARL MENDENHALL.

JUNIUS B. VAN HORN.

